[Nouveau] [RFC] Remove AGP support from Radeon/Nouveau/TTM

[Thomas Zimmermann]

Hi

Am 11.05.20 um 19:17 schrieb Christian König:
> Hi guys,
> 
> Well let's face it AGP is a total headache to maintain and dead for at least 10+ years.
> 
> We have a lot of x86 specific stuff in the architecture independent graphics memory management to get the caching right, abusing the DMA API on multiple occasions, need to distinct between AGP and driver specific page tables etc etc...
> 
> So the idea here is to just go ahead and remove the support from Radeon and Nouveau and then drop the necessary code from TTM.
> 
> For Radeon this means that we just switch over to the driver specific page tables and everything should more or less continue to work.
> 
> For Nouveau I'm not 100% sure, but from the code it of hand looks like we can do it similar to Radeon.
> 
> Please comment what you think about this.

It's probably not much of a problem in practice.

I guess everyone who plays 3d games has upgraded to something newer.

Wrt desktops, I found that some components of modern desktops (KDE,
Gnome) now have a hard requirement on SSE2. [1][2] But AGP is mostly
used in old 32-bit systems, which don't have SSE2.* So remaining users
of the GART functionality probably don't use any of these desktops.

The simpler WMs are usually usable with only little VRAM. At least they
should not be hit by any performance penalty.

Best regards
Thomas

[1] https://bugzilla.opensuse.org/show_bug.cgi?id=1162283
[2] https://bugzilla.opensuse.org/show_bug.cgi?id=1077870

* First-generation Athlon 64 have SSE2 and AGP support. But there are
few systems. Around that time AGP was replaced by PCIe.

> 
> Regards,
> Christian.
> 
> 
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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